Rollup merge of #106799 - scottmcm:remove-unused-generics, r=cuviper

Stop having unused lifetimes on some `impl`s

See <https://doc.rust-lang.org/nightly/std/cmp/trait.PartialOrd.html#impl-PartialOrd%3COsStr%3E-for-PathBuf>, where these lifetimes show up even though they're not needed:
![image](https://user-images.githubusercontent.com/18526288/212257802-da275167-38f9-4e2c-aafc-d44f0fc6a7c6.png)

With this PR, the unneeded lifetimes are no longer there:
![image](https://user-images.githubusercontent.com/18526288/212257938-0097c4bf-1247-4c91-8445-5bf0dde1b501.png)

Author: Yuki Okushi

library/std/src/path.rs

@@ -3177,33 +3177,33 @@ impl<'a> IntoIterator for &'a Path {
 }
 
 macro_rules! impl_cmp {
-    ($lhs:ty, $rhs: ty) => {
+    (<$($life:lifetime),*> $lhs:ty, $rhs: ty) => {
         #[stable(feature = "partialeq_path", since = "1.6.0")]
-        impl<'a, 'b> PartialEq<$rhs> for $lhs {
+        impl<$($life),*> PartialEq<$rhs> for $lhs {
             #[inline]
             fn eq(&self, other: &$rhs) -> bool {
                 <Path as PartialEq>::eq(self, other)
             }
         }
 
         #[stable(feature = "partialeq_path", since = "1.6.0")]
-        impl<'a, 'b> PartialEq<$lhs> for $rhs {
+        impl<$($life),*> PartialEq<$lhs> for $rhs {
             #[inline]
             fn eq(&self, other: &$lhs) -> bool {
                 <Path as PartialEq>::eq(self, other)
             }
         }
 
         #[stable(feature = "cmp_path", since = "1.8.0")]
-        impl<'a, 'b> PartialOrd<$rhs> for $lhs {
+        impl<$($life),*> PartialOrd<$rhs> for $lhs {
             #[inline]
             fn partial_cmp(&self, other: &$rhs) -> Option<cmp::Ordering> {
                 <Path as PartialOrd>::partial_cmp(self, other)
             }
         }
 
         #[stable(feature = "cmp_path", since = "1.8.0")]
-        impl<'a, 'b> PartialOrd<$lhs> for $rhs {
+        impl<$($life),*> PartialOrd<$lhs> for $rhs {
             #[inline]
             fn partial_cmp(&self, other: &$lhs) -> Option<cmp::Ordering> {
                 <Path as PartialOrd>::partial_cmp(self, other)
@@ -3212,40 +3212,40 @@ macro_rules! impl_cmp {
     };
 }
 
-impl_cmp!(PathBuf, Path);
-impl_cmp!(PathBuf, &'a Path);
-impl_cmp!(Cow<'a, Path>, Path);
-impl_cmp!(Cow<'a, Path>, &'b Path);
-impl_cmp!(Cow<'a, Path>, PathBuf);
+impl_cmp!(<> PathBuf, Path);
+impl_cmp!(<'a> PathBuf, &'a Path);
+impl_cmp!(<'a> Cow<'a, Path>, Path);
+impl_cmp!(<'a, 'b> Cow<'a, Path>, &'b Path);
+impl_cmp!(<'a> Cow<'a, Path>, PathBuf);
 
 macro_rules! impl_cmp_os_str {
-    ($lhs:ty, $rhs: ty) => {
+    (<$($life:lifetime),*> $lhs:ty, $rhs: ty) => {
         #[stable(feature = "cmp_path", since = "1.8.0")]
-        impl<'a, 'b> PartialEq<$rhs> for $lhs {
+        impl<$($life),*> PartialEq<$rhs> for $lhs {
             #[inline]
             fn eq(&self, other: &$rhs) -> bool {
                 <Path as PartialEq>::eq(self, other.as_ref())
             }
         }
 
         #[stable(feature = "cmp_path", since = "1.8.0")]
-        impl<'a, 'b> PartialEq<$lhs> for $rhs {
+        impl<$($life),*> PartialEq<$lhs> for $rhs {
             #[inline]
             fn eq(&self, other: &$lhs) -> bool {
                 <Path as PartialEq>::eq(self.as_ref(), other)
             }
         }
 
         #[stable(feature = "cmp_path", since = "1.8.0")]
-        impl<'a, 'b> PartialOrd<$rhs> for $lhs {
+        impl<$($life),*> PartialOrd<$rhs> for $lhs {
             #[inline]
             fn partial_cmp(&self, other: &$rhs) -> Option<cmp::Ordering> {
                 <Path as PartialOrd>::partial_cmp(self, other.as_ref())
             }
         }
 
         #[stable(feature = "cmp_path", since = "1.8.0")]
-        impl<'a, 'b> PartialOrd<$lhs> for $rhs {
+        impl<$($life),*> PartialOrd<$lhs> for $rhs {
             #[inline]
             fn partial_cmp(&self, other: &$lhs) -> Option<cmp::Ordering> {
                 <Path as PartialOrd>::partial_cmp(self.as_ref(), other)
@@ -3254,20 +3254,20 @@ macro_rules! impl_cmp_os_str {
     };
 }
 
-impl_cmp_os_str!(PathBuf, OsStr);
-impl_cmp_os_str!(PathBuf, &'a OsStr);
-impl_cmp_os_str!(PathBuf, Cow<'a, OsStr>);
-impl_cmp_os_str!(PathBuf, OsString);
-impl_cmp_os_str!(Path, OsStr);
-impl_cmp_os_str!(Path, &'a OsStr);
-impl_cmp_os_str!(Path, Cow<'a, OsStr>);
-impl_cmp_os_str!(Path, OsString);
-impl_cmp_os_str!(&'a Path, OsStr);
-impl_cmp_os_str!(&'a Path, Cow<'b, OsStr>);
-impl_cmp_os_str!(&'a Path, OsString);
-impl_cmp_os_str!(Cow<'a, Path>, OsStr);
-impl_cmp_os_str!(Cow<'a, Path>, &'b OsStr);
-impl_cmp_os_str!(Cow<'a, Path>, OsString);
+impl_cmp_os_str!(<> PathBuf, OsStr);
+impl_cmp_os_str!(<'a> PathBuf, &'a OsStr);
+impl_cmp_os_str!(<'a> PathBuf, Cow<'a, OsStr>);
+impl_cmp_os_str!(<> PathBuf, OsString);
+impl_cmp_os_str!(<> Path, OsStr);
+impl_cmp_os_str!(<'a> Path, &'a OsStr);
+impl_cmp_os_str!(<'a> Path, Cow<'a, OsStr>);
+impl_cmp_os_str!(<> Path, OsString);
+impl_cmp_os_str!(<'a> &'a Path, OsStr);
+impl_cmp_os_str!(<'a, 'b> &'a Path, Cow<'b, OsStr>);
+impl_cmp_os_str!(<'a> &'a Path, OsString);
+impl_cmp_os_str!(<'a> Cow<'a, Path>, OsStr);
+impl_cmp_os_str!(<'a, 'b> Cow<'a, Path>, &'b OsStr);
+impl_cmp_os_str!(<'a> Cow<'a, Path>, OsString);
 
 #[stable(since = "1.7.0", feature = "strip_prefix")]
 impl fmt::Display for StripPrefixError {